As a part of our research process leading up to 2.0, we analyzed usage statistics of the API to date. For the period from 8/21/2011 to 9/21/2011 inclusive, there were 34.2 million requests against the API. That’s about 12 requests per second.

API usage skews heavily toward users and questions:

The top API calls, by volume, are:

/users/{ids}/timeline

7.8m

/users/{ids}

5.2m

/users/{ids}/mentioned

4.2m

/questions

3.4m

/questions/{ids}

3.0m

/users/{ids}/questions

2.9m

/questions/{ids}/answers

1.7m

/users/{ids}/reputation

1.3m

/users/{ids}/answers

1.3m

/posts/{ids}/comments

1.3m

/answers

463k

There’s a precipitous drop in usage after that. It’s somewhat surprising just how user centric the queries are, given how Q&A focused Stack Exchange sites are. This suggests that user authentication to get to the tiny bit of hidden user information we have really will be a popular feature — and that is slated for API V2.0.

Approximately 6% of API traffic is the result of internal Stack Exchange requests. Chat made approximately 1.1m requests, stackexchange.com made about 250k requests, and careers.stackoverflow made approximately 140k requests. Only Chat actually requires the raised API request limit that we give it.

Roughly 59% of all API requests are from non-web applications. Of the top 20 applications, 8 are non-web applications. This is of some interest with regards to the debate around HTML encoding all output by default, to ensure it is HTML safe. This suggests that there are many opportunities for script injection, although the reach of the attack is somewhat mitigated.

API usage growth is basically flat. This is not terribly surprising, since we’re read-only until API v3.0.

Getting cache hit rates out of our logs is a bit difficult, but we’ve got an upper limit of 10% based on the numbers. I’d say we can be confident in a 3-5% cache hit rate.

We hope these statistics are interesting, if for nothing else than learning about some useful apps that work with the Stack Exchange API that you might not have heard of. You can find out more about these apps, and discover a bunch more, at Stack Apps!

Stack Apps is more than an app (and script) directory — there’s also a comprehensive set of documentation, support, and examples for the Stack Exchange API over at Stack Apps — and the entire API is self-documented at …

giving them their very own script tab on the homepage powered by the [script] tag.

updating the /faq and introductory messages to emphasize that browser scripts which enhance the Stack Exchange experience are welcome, even if they don’t technically use the API.

continuing to publicize the cool and useful scripts our community is creating from within our own community.

If you’re wondering how browser scripts work, the good news is thatGreaseMonkey support is almost standard across most major browsers now. We updated the script tag wiki to walk you through the process of installing user scripts in your browser. It’s easy — really!

That’s a very, very simple browser user script which hides the question answer form on Stack Overflow. If you’re using Google Chrome for example, all you need to do to install that little fragment of code in your web browser is click the no-so-answers.user.js link — like so:

User scripts can be managed by clicking the wrench icon in the toolbar and selecting Tools | Extensions, or of course by entering chrome://extensions in the title bar.

That’s how easy it is!

We’ve already contacted everyone via email who had user scripts posted on Meta Stack Overflow. We’d like to get those all migrated to Stack Apps so the community has one place to go for a centralized directory of cool, useful scripts that make our sites work better.

So if you have a cool user script that works on a Stack Exchange site, and you think others might find it useful or interesting, please list your script on Stack Apps!

Rebecca took an informal survey of the API developer community at Stack Apps, and determined that what everyone wanted most (beyond v2 of the API, yes, I know) was an improved application gallery. So we’ve made the default page on the site the application gallery, and spruced it up to be more visually friendly to average users.

This should make it easier for Stack Exchange users to find your app and start using it!

Do bear in mind that we heavily promote stackapps.com both with house ads, and in the footer of every Stack Exchange site we launch. So developers, we have your back. If you build on our API, we will continue to fully support you in every way we can!

It was tough judging winners between so many fantastic entries. I encourage you to browse the complete list of apps and libraries to see for yourself how much cool stuff the community created. Whatever your platform of choice, there’s something here for you to work with, learn from, and perhaps even contribute back to.

Most Entries

We’re awarding Lilliput USB Monitors to two members of the community who single-handedly contributed a huge number of apps and libraries to the contest.

Third Place

Six to Eight is a free, pocket sized iOS client, for you to track your activity and get answers to those niggly, “need an answer right now” problems. Full browsing, searching, statistics and user tracking. App Store link (free)

First Place

StackTack is a widget for bloggers and writers to easily tack questions and answers from the Stack Exchange sites such as Stack Overflow, Server Fault and Super User, into their articles. The widget remains up to date as answers get added, modified, voted on and accepted.

30″ Dell or Apple LCD winner

We’ve contacted all the winners via email and we’ll be arranging shipment of your prizes ASAP. Additionally, anyone with an entry in the contest that had 3 or more score at the time of judging was sent a Stack Overflow, Server Fault, or Super User t-shirt of their choice — and naturally a bunch of stickers.

Congratulations to everyone who entered the contest. Your feedback helped us drive the API forward and make it better for everyone — but most importantly, you built amazing apps and libraries!

Your app must work against the final, 1.0 released version of the API. We’ll give you at least a week’s notice here on the blog when that’s closer to happening.

Well, if you’re planning to enter this contest, you might want to get a move on — the 1.0 release of the Stack Exchange API is imminent! We plan to bless 1.0 of the API this Friday, July 9th.

Due to the many Area 51 sites we’re launching, things are a bit busy. That’s good news, though, for my fellow procrastinators — it means we’re extending the deadline for the API contest slightly. We now plan to pick the contest winners in the first week of August.

So, if you’re thinking of entering the contest, you still have a few weeks to build something prize-worthy.